1. Field of the Invention
The present invention relates to an AC/DC adapter and a notebook computer using the same, and more particularly to an AC/DC adapter having an additional grounding jack and a notebook computer using the same.
2. Description of the Related Art
An AC/DC adapter is generally used to convert AC power into DC power and supply DC power to various electronic devices such as a notebook computer. As shown in FIG. 4, a conventional notebook computer 110 has a computer main body 111 mounted with a central processing unit (CPU) (not shown). A docking station 121 is detachably connected with the computer main body 111 to expand a computer system and cooperate with the computer main body 111. A connection port 113 and 123 is selectively connected to a power supply jack (not shown) of an AC/DC adapter 130 to supply DC power through a power cord 135 from the AC/DC adapter 130. Additionally, the computer main body 111 and the docking station 121 are electrically connected by a connector 127. The connector 127 receives/sends data between the computer main body 111 and the docking station 121.
Thus, to use a notebook computer 110, a user may connect the power supply jack of the AC/DC adapter 130 to either of the connection ports 113 and 123 of the computer main body 111 or the docking station 121.
In a notebook computer system 110 in which the computer main body 111 and the docking station 121 each constitute an independent system, it is very important that the potential difference between the computer main body 111 and the docking station 121 is removed to reduce EMI(electromagnetic interference).
Here, if the AC/DC adapter 130 is connected only to the connection port 123 of the docking station 121 and not to the grounding area 115 of the computer main body 111, the ESD (electrostatic discharge) current generated from the computer main body 111 is discharged to the earth 129 through the grounding area 115 of the computer main body 111, the connector 127, the grounding area 125 of the docking station 121, and the AC/DC adapter 130.
In the conventional notebook computer, each grounding area of the computer main body 111 and the docking station 121 is connected, but only by the connector 127, so that the grounding connection is not adequate with regard to EMC (electromagnetic compatability). That is, the grounding connection between the computer main body 111 and the docking station 121 through the connector 127 is not sufficient to remove the electromagnetic interference. Further, in the conventional notebook computer, the ESD current generated from the computer main body 111 is discharged to the earth 129 through the long grounding path formed through the connector 127, the docking station 121 and the AC/DC adapter 130, thereby causing damage to each of the circuit systems of the computer main body 111 and the docking station 121.